There are a number of surgical procedures for the eye in which a therapeutic medium is instilled postoperatively in or on the eye as well as a number of therapeutic or treatment procedures in which a therapeutic medium or another medium or fluid is instilled on the eye topically. For example, for Lasik, cataract and other refractive procedures anti-inflammatories such as-steroids and anti-infective drugs are topically administered post-operatively. Also, the treatment of corneal diseases such as corneal melts or post-operative management of corneal transplants also can involve the topical delivery of drugs to the eye. Further, drugs or therapeutic mediums are delivered topically for the treatment of inflammatory eye disorders or eye infectious disorders.
In addition to the administering of drugs postoperatively and/or prophylactic administration for treatment of eye disorders or diseases, there also can arise a need to maintain a desired level of moisture postoperatively as well for treating what is commonly referred to as dry eye over a short period or long period of time. With reference to FIG. 1, the lacrimal glands continuously secrete tears that bathe the cornea and conjunctiva of the eye that moisten these tissues as well providing a vehicle for removing or washing away foreign substances (e.g., particles) that alight on the external surface (e.g., conjunctiva) of the eye. As the tears being secreted drain from the eye through the nasolacrimal duct, the drainage of the tears may make it difficult to achieve the desired level of moisture. It also is possible that the amount of fluid that can be secreted is insufficient for achieving the desired level of moisture such as that which occurs with the dry eye condition.
There exist a wide range of procedures or techniques for accomplishing such treatment. In one technique, plugs, sometimes referred to as punctum plugs are inserted using appropriate medical techniques/procedures into at least one of the two punctums of the affected or given eye. The inserted plug occludes the at least one punctum thereby preventing the flow of any tears or fluid through the occluded punctum, to the tear drainage ducts (upper lacrimal canaliculus and lower lacrimal canaliculus) and thus through the nasolacrimal duct. With such plugging of a punctum, the tears or fluid being secreted do not easily drain from the eye and thus are retained in the eye. This is so because the secreted tears only can escape the eye either by flowing through the punctum that is not plugged or by the tears or fluid overflowing and exiting the eye such as that seen when one cries. In other techniques, the individual directly administers or topically administers artificial tears, restasis, allergan or other agents to the treatment the drying eye condition.
Treatment of ophthalmic conditions using drugs applied directly to the eye in either liquid or ointment form, (i.e., topical administration) is generally effective for treating problems involving the superficial surface of the eye and diseases that involve the cornea and anterior segment of the eye, such as for example, conjunctivitis. As indicated above, however, such topical eye drops, however, can drain from the eye through the nasolacrimal duct and into the systemic circulation. As a consequence, the medication available for treatment is thus diluted or reduced and the drainage also increases the risk of unwanted systemic side effects. Further, data also indicates that it is not unusual for up to 85% of topically applied agents to be removed by the eye's blink mechanism/reflex. In addition the conventional technique of delivering drugs in the form of topical eye drops is of little utility because the drug can be highly unstable and therefore not easily formulated for topical delivery.
The use of a topical insert for direct delivery of drugs to the eye has been contemplated/attempted, however, this method has been found not to be desirable as such conventional topical inserts typically require patient self-administration and thus education on their insertion into and removal from the eye. Consequently, this particular technique demands a certain degree of manual dexterity that can be problematic for geriatric patients who are particularly susceptible to certain eye disorders that appear age related. Also, in many instances such topical inserts may cause eye irritation and such conventional inserts are prone to inadvertent loss due to eyelid laxity. Further, as with topical administration techniques described above, the drug being delivered by such a topical inset is drained from the eye through the nasolacrimal duct and into the systemic circulation, thereby diluting or reducing the amount of the drug that is available for treatment and the drainage also increases the risk of unwanted systemic side effects. Thus, such conventional direct delivery devices have limited, if any at all, utility for providing an effective source of drugs.
It thus would be desirable to provide a new device that provides a more effective pathway for controlled, direct delivery or administration of drugs, therapeutic mediums or other treatment mediums to the eye as well as providing new methods, for delivery of such drugs, therapeutic mediums or other treatment mediums (e.g., artificial tears) to the eye using such devices. It would be particularly desirable to provide such a device and method that would be more effective in delivering the medium topically as well as being retained within the eye in comparison to the prior art technique of direct delivery of the treatment medium/drug. It also would be desirable to provide such a device that can be adapted to delivery any of a number of drugs, therapeutic mediums, or other treatment mediums without changing the basic delivery concept. It also would be desirable to provide such a device that is adapted for removable insertion into an exiting bodily orifice of the eye, the punctum, whereby the device is retained there during normal eye activity as compared to prior art devices. It also would be desirable to provide a device that is adapted to provide a controllably releasable source of drugs, therapeutic medium or other treatment medium for administration over a desired period of time as compared to existing topical administration techniques.